The present invention is related to a process for the preparation of essentially bacteria-free colostrum.
Colostrum, or first milk, is the breast milk which is secreted by mammals during the last part of pregnancy and the first few days after pertuision. Colostrum obtains a little less fat than the later milk and is rich in proteins, especially immunoglobulins. Colostrum possess a number of out-standing and interesting properties, a.o. owing to the high nutritional value. The proteins in colostrum, and especially immunoglobulins, have a wide range of uses.
Bovine colostrum may also contain a high number of bacteria, about 106-108 bacteria/ml. However, problems have been present for a long time relating to methods to reduce the bacteria content in colostrum for thereby to be able to produce a bacteria-free colostrum composition.
Heat sterilization (pasteurisation) of colostrum to remove the bacteria is not possible because heating will denature and coagulate the proteins (this is especially important in relation to biologically active proteins).
A common prior art method for sterilizing solutions is microfiltration. However, microfiltration of colostrum has not been possible so far, because the casein in colostrum immediately clogs the microfilters and makes the filtration impossible (see German Patent C 2 813 984).
PCT Application Wo 85/10192 describes a nutritional drink based on colostrum. This product was sterilized, after separation of the fat from the colostrum with a conventional method, by removing the casein by precipitation (with hydro-chloric acid) followed by microfiltration of the resulting xe2x80x9cwheyxe2x80x9d.
U.S. Pat. No. 5,147,548 describes preparation of a sterile-filtered colostrum with a retained casein content. According to the method of this publication a defatted colostrum solution is acidified with hydrochloric acid until the casein precipitates at a pH of 4-5 and then returns to solution by lowering of the pH to 2-3.5. Then, the colostrum solution can be microfiltrated and the pH of the solution is subsequently returned to the original value by adding NaOH. Thus, such a method requires, in addition to the micro-filtration, two additional steps which make the procedure for the preparation of bacteria-free colostrum more complicated and far more expensive. In addition, product obtained by this method is not a xe2x80x9cnaturalxe2x80x9d colostrum, owing to the addition of an acid, followed by a base, which results in a higher salt content than in xe2x80x9cnaturalxe2x80x9d colostrum. It is also an open question whether these additions of acids and alkali will effect and change the natural proteins in colostrum (especially the valuable immunoglobulins).
By the present invention it was surprisingly discovered a process by which, after the fat had been removed, natural colostrum, including the casein, could be micro-filtrated. This process provides a colostrum composition wherein the bacteria content is reduced up to 99.9%, and otherwise wherein all the natural components, besides fat, are retained without application of any additives or complicating and demanding supplementary treatments. All the previously preformed attempts in the prior art of directly micro-filtration of defatted colostrum have been unsuccessful, an in U.S. Pat. No. 5,147,548, column 1, it is concluded that: xe2x80x9cFiltration sterilization, the simplest and most effective method of eliminating the bacteria and the method that protects the proteins, cannot be employed with colostrum because the casein immediately clogs up the filterxe2x80x9d.
By the present invention it was surprisingly discovered that colostrum can be microfiltrated by using a larger booster pump and increasing the velocity of the concentrate.
In a common microfiltration of milk the booster pump rate (the milk which flows through filter) is 6 m3/hour. In microfiltration of colostrum the filter will clog up at this rate.
By the present invention it was surprisingly discovered that colostrum can be microfiltrated by using a larger booster pump and increasing the velocity of concentrate to between 7.2 and 7.8 m3/hour.
Thus, the present invention provides a process for microfiltration of natural, defatted colostrum for the preparation of an essentially bacteria free (99.9%) colostrum wherein the original components (especially the protein composition) are retained in essentially native form and without any use of additives.
Thus, the process of the present invention for the preparation of essentially bacteria free colostrum comprises:
Defatted colostrum is poured into a balance tank; subsequently the concentrate is transported to a booster pump by means of the feeding pump; the booster pump circulates the concentrate across a membrane wherein the pressure difference in the membrane will provide filtration of the concentrate; the concentrate flows across a heating/cooling equipment to maintain a constant operating temperature prior to returning to the booster pump; the filtered colostrum (filtrate) circulates across the filter to maintain a constant transmembrane pressure; the filtrate is drained in the filtrate side of the filter without reduction of pressure.
The process of the present invention is illustrated by the following, non-limiting, example, and FIG. 1, which is a schematic drawing of a non-limiting example of a micro-filtration device used in the microfiltration process of the invention.